There are two main groups of power amplifier in an NVA hi-fi system:
- Stereo: Two channel amps - inc. S80, S150 & S300.
- Mono-block: Single channel amps (in matching pairs) - inc. M300 & M600.
P50 PRE-AMP PLUS SINGLE STEREO POWER AMP
Stereo models are the most common and integrate power supply and two channels of amplification in a single unit. This set up forms the entry point into an NVA pre/power system with the P50 pre-amp and S80 power amp.
P50 PRE-AMP PLUS MONO-BLOCK POWER AMPS
Mono-block power amps are actually two boxes, and come in matched left / right pairs. Each channel is completely independent of the other, and results in less interference between left and right channels, giving better stereo imaging, but the greatest advantage is that each channel has its own power supply, or dual power supplies in the case of the M600. This results in greater dynamics and incite into the music.
The P50 preamp has three sets of outputs per channel, so we can support bi-amping (and also tri-amping for speakers with this capability).
For example, we can add the M300 or M600 mono-block power amps to a system that contains a single stereo power amp. Now our stereo power amp is driving just the tweeters, relieving it of the low frequency current needed to drive bass units. The result is lower distortion, more detail and sweetness. Each mono-block drives only a single bass unit and much less crossover. This results in much less inter-modulation giving better bass and mid-range.
If we already have mono-block amps, we can either add a stereo power amp to replicate the above system, or we can add a 2nd set of mono-block amps to give even greater performance.
Some multi-driver speakers have 3 sets of speaker terminals, allowing you to use separate amps for bass, midrange and treble units. The principles and benefits are the same as bi-amping.
WHEN BI-AMPING IS NOT POSSIBLE
Not all speakers can be multi-amped, some have only a single pair of binding posts. In this case we can not obtain better sound with multi-amping. Instead we must simply use better amplifiers, for example a pair of M600 mono-blocks.
MULTI-AMPING VS SINGLE AMPING
What's better? S150 + M300s or a single pair of M600s? If your speaker has a complex or high-order crossover, or has a uneven impedance curve (especially around the crossover point) then multi-amping is probably the better route to take. In fact, we would always recommend the multi-amp route for speakers with 3rd or 4th order crossovers, as each amplifier then 'sees' less crossover. If your speaker has simple (low-order) crossover networks, and even impedance curves, then we recommend either solution.